In a bowl, mix the onion, cinnamon, nutmeg and oil. Add the chicken pieces and stir to coat. Let stand for 10 minutes.

Place
chicken, marinade, and all remaining ingredients in the base of a
tagine. Cover, and cook over lowest heat for an hour, stirring
occasionally, breaking up the prunes as they soften, until the chicken
is tender and the prunes have reduced to a thick sauce. Be patient –-
this will turn from a thin, watery sauce to thick and a nice dark
mahogany color, towards the very end of the cooking time. Keep an eye
on it and stir occasionally. When the sauce is thick and most of the
liquid is gone, the dish is done. Serve with couscous or warm bread.